A Thesis Submitted in Partial Satisfa.Etion of the Reqhi:Cements for the Degree of }Laster of Science In
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Cl>J:.IFOENLA. STATE UNIVERSITY, NORTHRIDGE ECOLOGY OF FERAL HOUSE CATS (Fel-i.s domestiaa) _,,;>_ ON SANTA CATALINA ISLAND, CP.LIFOfu~I.A A thesis submitted in partial satisfa.etion of the reqhi:cements for the degree of }laster of Science in BIOLOGY by Paul David Lonquich August, 1979 The Thesis of Paul David Lonquich is approved: ----- George F. Fis~ ~h~ R. Swanson Andrew Starrett, Committee Chairman California State University, Northridge ii p ' AC1..'NOWl.EDGMENTS The many years I have spent at California State University) North ridge have been most :memorable; in fact 313 has been my second home. I am deeply grateful to Dr. Starrett and Dr. Fisler for providing me with a >vork ar.ea and many stimulating conversations. The many friend-· ships vihich developed in the .i.ab Hill be long remembered~ but special appreciation goes out to Stephan C. Lenchner and Chuck Bufalino, each of whom helped me in their own special way. I would also like to thank by committee for their help in preparing and reviewing this thesis. I extend thanks to Dr. Andrew Starrett for serving as my tl1esis committee chairman~ his help on this project is greatly appr.eciated and his friendship will always be cherished. Profes sors George F:isler and John Sw2nson, the other members of my comm.i.ttee, demonstrated great guidance and patience over the Eemesters which helped me townrd the completion of this thesis. For statistical advice and help with the computer analysis, I thank John S"1anson, Davi.d Hull, and Bruce GE:lvin. I would be remiss not to mention the staff of the Biology department. Robert Botts and Pam-Friedman in the stockroom have gone out of their w.ay many times to help me acquire the necessary equi.pment~ and in the office Sarah Yucht and Grace Davis have always been helpful, for this I am most grateful. A special thanks to Dr. Keneth Jones who arranged for m•e to receive cats from the Rest Valley P...nimal Shelter. Without t.he support and help from the Santa Catalina Island Con servancy this project would not have been possible. Mr~ A. Douglas Probst and. th2 staff of the conservancy were helpful throughout my stay i.ii on Catalina. Mr. Probst arrr.mged with Mr. Richard Whe0ler, Headmaster of Ca.talina Island School, f.o:c me to use the donnatories at the school. My stay at CIS -was enhanced by the thoughtfulness and generosity of the entire staff and faculty, especially Marge Lewis. The Santa Catalina Island Company allowed me t.he use of their library and supplied tech nical information about: the Island. The Catalina Camp and Cove Company allowed me the use of J.... ittle Fisherman Campground as my isthmus base. Dr~ Rober·: Gi;;en, of the USC Center for Marine Seience, allo~ve.d me to use the freezer at the station to store my cats. Finally I am especially indebted to my parents for thei!' love and understanding which helped me through the tough times and made the good times that mueh bette1:. I dedicate this thesis to them as a smEll token. of my apprec:i.ad.. on, knowing I' 11 never be able to -really repay them for all they have done. I would also ljke to ~~hm.1k B.los3on Lenchne1· for hel:' umvaivering c.onfidence in my abilit~ies and her continued support. iv TABLE OF CONTENTS Page Ackno"Jledgments iii Table of Contents v Tables vi Fi~::ures vii Absr.ract viii Introduction 1 Methods and Haterials 9 Results 25 Discussion 54 Feral Cats 54 Ec.ology of the Feral Cat 64 Food Habits of Feral House Ca+-.s 68 Reproduction Ratio and Wild Breeding 75 :E,;tternal Measurements 79 r , . •_,QUC.LUSl.On 82 Summury 84 Appendex A 86 Litara~ure Cited 92 TABLES Number Page 1 C~pture - Recapture data 28 2 Food items found in Catalina eat digestive tracts 29 3 Digestive tract analysis of cats sampled from Cat.alina 30 4 CharacteY.s which are significantly di.ffe.rent at the 0.05 level or better :n 5 Results of REITH program 5a Found cats I Catalina cats 32 5b ¥~le cats I Female cats 5c Island male I Island femaie 36 5d Pound male / Pound femlae 38 6 t-·Tests between characters 6a Povnd cats I Catalina cats 40 6b Hale cats I Fema1e cats 42 6c Island m~le I Island female .44 6d Pound male I Pound female 6e Pound male I Island male 48 6£ Pound female / Island female 50 7 Cb.aracteris tics for separati-:1g feral £:rom noo.-·feral cats 62 8 Ratio of males to female house eats found in the. wild 77 vi FIGURES Page 1 Location of the eight California Channel Islands 5 2 Santa Catalina Island (trap sites) 12 3 Aerial photograph of Toyon Bay 14 4 Descripticn of skull measurements taken on all eate 22 5 Phenogram utilizing discriminant scores and using minimum variance clustering option 52 vii ABSTRACT ECOLOGY OF FERAL HOUSE CATS (Felis domest'tea) ON SANTA CATALINA ISLAND, CALIFORNIA by Paul David Lonquich Master of Science in Biology Santa Catalina Island, twenty-two miles off the southern California coast, Has the site of a study on the ecology of feral house. cats (l!elis dcmest-ic~a.). Observation of behavior~ physical characteristics and capture sites were used to determine whether a cat was existing in a feral state. All cats observed or captured on the island \.rere in good physical condition, appeare.d to prefer dense ch.:!parral \dth rocky outcroppings and \vere more abundant near dumps and >mter supplies~ Exa.minat:ion of the digestive tracts of tvJenty-three cats revealed cer t3.in fot1d prr::fen~nces; 95% of the digestive tracts contained insects, SUs had vegetation, and 64% had garbage, rodent remains were found in viii 41%~ bird remains in 22%, and reptil:Lan forms in_ 23%. Digestive tracts o£ 68% of the ea.ts had internal parasites. A c.omputer analysis of factors which would discriminate between t.he island sample and a sample collected from the West Valley Animal Shelter!~ Chatsworth, California was performed. The analysis showed that the length of the maxillary tooth rm·l, t.he tympanic bull.a length, the greatest width of the zygom&tic arch &nd the mandibular .length were the most powe:rful discriminating measuremt:nts. r·t is suggested that stronger ·controls be placed on ca.t O\>,TJ.le:rs to eliminate the constant drift of cats from populated are3s in conjuction with the gradual elimination of feral cats already on the :Lr;land. ix INTRODUCTION Off the coast of Southern California lies a group of eight islands. ·The third largest of these islands was discovered in 1452 by Cahrillo who named it Sa.n Salvador. Sixty years later it was y·ediscovered by Vizcaino ~vho :named it Santa Catalina. First controlled by Spain and then by Mexico, the first American owner of Catalina Island was Thomas Robbins, who acquired it in 1846 by land grant fn'm Pi.o Pico, ·the last Nexican Governor in control of Catalina. The Island changed hands sev- e-ral times before most of it was acquired by the Banning Brorhers \vho incorporated the Santa Catalina Island Company in 189LI. Pr2sent u\-rner- ship of the island and that company stems from stock purchases :made by William Wrigley Jr. in 1919 through which he acquired majority intF:rest in ·the company~ In 1972 the Santa Catalina Island Conservancy was set up as a pri- vat.e nonprofit operating foundation with the aim of making most of Santa Catalina Island a permanent nature preserv-e. In 1974~ an easement agreement ¥las signed, giving Los Angeles County the right to share the use of !fl,OQO acres of Catalina's interior and much of its coastlinE' for park conservation and recreation uses·for 50 years. In 1975, the Santa Catalina Island Conservancy acquired title t.o 4 2,135 acres: in- eluding virtually all of the 41,000 acres covered by the easement agreement with the County. Now the Co!lservancy Ow'IlS and, in cooperation wit~ the Couvty, operates about 86% of the island's 76 square miles. Feral cats have been the topic of many studies. McKnight (196!1) in his work on feral animals described the feral cat as one that was 2 once dorr:est:i.cated, or ll<lith dolliestic an.cestors 1 •vhich is now living in a. wlld state. Cats have the· ability to shift from a domestic state in to a vTild state and back again) thus making it difficult to identify a true feraL Nilsson (1940) in his study of cats found several behavioral and physj_c.al characteristics which aid;:d in. distinguishing feral fro:n .. non-·fe:ral cats. The :mcst studied aspect of the life of a feral cat is its food. habits (Errington, 1936; Nilsson, 1940; McMurry and Sperry~ 1941; Eradt, 1949; Hnbbs, 1951; Parmalee, 1953; Eberhard, 1954; Toner, 1956; Nader an.d .Hartin, _1_962; Pearson~ 1964 and 1971; Coru.an anrl Br~wner~ 1971; Jones, 1977). These studies were of two types: Bradt (1949) and Toner (1956} obs.erved the prey their cats c:aught over a period of time; the others analyzed the digestive tracts of captur.e.ci csts and expressed as percentag2.s of prey per total. r..w.uber af ea1:s. These stud5 ~s indicated that eats prefeT mammals (rodents and 1ag•JmorphG partj_cuL1rly) ~ birds, reptiles, a.mphibians, fishes, inseets, carrion, human garbage, and pJ.ant material.